High-temperature geothermal exploration and drilling operations require a wide array of tools and sensors suitable for instrumentation for monitoring downhole conditions. There are limited options for tools and components with the capability for high temperature drilling and monitoring.
Several downhole applications exist in which a small motor may be useful. Applications such as clamping systems for seismic monitoring, televiewers, valve actuators, and directional drilling systems may be able to utilize a robust motor controller capable of operating in harsh environments.
Current motor controllers are capable of operating up to 125° C. The development of a high-temperature motor controller capable of operation at temperatures greater than 125° C. and up to 230° C. would significantly increase the operating envelope for next generation high temperature tools and provide a useful component for downhole systems. Recently as motors capable of operating in very high-temperature regimes are becoming commercially available, but motor controls are not available for application in such environments. One method of deploying a motor controller is to use a heat shielded tool and apply low-temperature electronics to control the motor. This method limits the amount of time that controller tool can function in high-temperature environments and does not allow for long-term deployments. Heat shielded tools may be suitable for logging tools that spend limited time in the well. However, a longer-term deployment is not possible, e.g., for a seismic tool which may be deployed for weeks or even months at a time.
What is needed is a reliable and robust method for long-term deployments and long-life operations, which uses high-temperature electronics and a high-temperature motor that does not need to be shielded.